INVESTIGATION OF MODE SCATTERING BY HARD STRIPS IN LINED DUCTS USING COLLOCATION | ||
| International Conference on Aerospace Sciences and Aviation Technology | ||
| Article 2, Volume 11, ASAT Conference, 17-19 May 2005, May 2011, Pages 19-30 PDF (2.31 M) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/asat.2011.27137 | ||
| Author | ||
| Elnadi T. | ||
| Assistant Professor, Sound and Vibration Lab., Faculty of Engineering, Ain Shams University, Cairo, Egypt. | ||
| Abstract | ||
| When mounting acoustic liners inside the inlet duct of aircraft jet engines, hard strips exist in-between liner sections in order to hold them in place. It has been generally acknowledged, from experiments, that the existence of hard strips inside lined ducts affects the attenuation behaviour of the duct. The acoustic energy is scattered and rearranged among different modes so that it might be transferred into modes which are less attenuated by the liner. Moreover, cut-off modes may scatter into cut-on modes. In this paper, flow is included in the locally reacting liner case, which is more interesting to the aeronautics applications. Moreover, the duct is made finite and connected to two semi-infinite hard inlet and outlet ducts. By using mode matching, it is possible to input any mode at the inlet side and to study the modes on the outlet side. Comparisons are made between different hard strip cases and the splice-less liner case. | ||
| Keywords | ||
| Acoustic liners; hard strips; Jet engine noise | ||
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